10.3 Analysing Circuits

Question 1

What is the effect on the total emf and total current in a circuit if an extra cell is added in series and in the same direction as the first cell

Answer 1

The emf would be greater therefore the total current would be greater

Question 2

What is the effect on the total emf and total current in a circuit if an extra cell is added in series and in the opposite direction as the first cell

Answer 2

The total emf would be lower therefore a lower total current

Question 3

What is the effect on the total emf and total current in a circuit if an extra cell is added in parallel with first cell

Answer 3

The total amount of energy supplied to the circuit increases however neither the total emf or current change

Question 4

How can a flat cell be recharged

Answer 4

By connecting it in series in the opposite direction to a cell that still has charge

Question 5

If you connect a voltmeter across the terminals of a power supply what s measured

Answer 5

Terminal p.d

Question 6

Why does the gradient of the i-v graph for a filament lamp decrease as V increases

Answer 6

As more current flows through the filament the temperature increases
The atoms and ions within the wire vibrate more therefore colliding more often with the electrons flowing through it = higher resistance
So the gradient of the graph decreases

Question 7

Describe the i-v characteristics for a diode

Answer 7

In the backwards direction = current is zero
In the forward direction = current is zero
Until the threshold voltage is reached then the current will flow

Question 8

Define 1kWh

Answer 8

The energy used by a 1kW appliance in 1 hour

Question 9

How is p.d distributed around a parallel circuit

Answer 9

The components in parallel have the same p.d

Question 10

How is terminal p.d calculated when no current flows

Answer 10

The terminal p.d is equal to the e.m.f of the source

Question 11

What is terminal p.d

Answer 11

The potential difference across an electrical power source